Project 1 has two primaryaims. The first isto collecta second wave of data, approximately9-10 years later,on the MIDUS I core sample (N -- 3,485), metropolitan over-samples (N = 757), twins (N = 998 pairs), and siblings (N = 951) of core respondents. At T2, respondentswill be 35 to 86 years of age, thereby allowing for investigation of age changes and differences in a wide array of behavioral, psychosocial, and experiential factors hypothesized to influence unfolding trajectories of health and illness. In the 4+ years since the data have been available, MIDUS I findings haveappeared in 42 journals covering numerous scientific fields. Data collection will largely repeat T1 assessments (45 minute phone interview, 100 page self-administered questionnaire) plus additions in select areas (e.g., cognitive functioning, optimism and coping, stressful life events, caregiving). The second primary aim is to recruit a Milwaukee, WI over-sample of African Americans (N= 400) to participate in a lengthy field interview and questionnaire paralleling the above instruments, designed to maximize response rates. The hypotheses to be investigated with MIDUS II are extensive, giventhe many investigators working with the data. An overarching theme across them is that behavioral and psychosocialfactors are consequential for health (mental and physical). Illustrative examples: regarding age-related resilience, we predict that aging individuals who show delayed onset of health problems, have fewer disabilities, and lower mortality are those with psychological strengths (e.g., emotion regulation, coping, control, goals/purpose, cognitive abilities, religious/spiritual beliefs), quality ties to others (e.g.,spouse, family, friends) and positive health practices. Regarding socioeconomic factors and health, we predict that behavioral and psychosocial factors are key mediators/moderators of SES-related effects on health. Regarding the African American sample, we predict that perceived discrimination and related measures of affect and coping will be linked with health outcomes, and intervening health practices. The neurobiological mechanisms through which these many behavioral and psychosocial variables influence health will be elaborated in Projects 4 and 5. Given the guiding objective of integrating these many levels of analysis in understanding pathways to health and illness, Project 1 will also include emphasis on person-centered methodologies to accomplish such integration. Revisions focus on clarifying guiding theory, documenting the high quality of the original MIDUS study, adjusting projected response rates, and articulating how the proposed research will advance existing paradigms in aging.